1. Field of Invention
The present invention relates to an ink composition, an ink set, and an inkjet image forming method.
2. Description of the Related Art
In recent years, as a result of ever-increasing demand for the protection of resources, protection of the environment, enhancement of operational stability and the like, the conversion of inks into aqueous products is advancing. As in the case of oil-based inks, the product qualities demanded from aqueous inks include fluidity, storage stability, glossiness of film, clarity, coloring ability and the like. However, compared to oil-based vehicles, most pigments have a markedly poor adaptability to aqueous vehicles with respect to pigment dispersibility and the like, and therefore, satisfactory product quality cannot be obtained by conventional dispersion methods. In the past, the use of various additives, for example, aqueous pigment dispersing resins or surfactants, has been examined, but an aqueous ink that satisfies all the adaptation properties described above and is comparable to existing oil-based inks having high product quality, has not been obtained.
In order to solve these problems, for example, an aqueous ink composition containing a colorant, which is coated by a water-insoluble polymer, as a color material, and polymer particles has been disclosed (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-329199). Further, an ink composition containing resin emulsion and inorganic oxide colloid has been disclosed (see, for example, Japanese Patent No. 3550637), and it is described that a good image can be formed.